Design And Test Of Microheater For Transmission Electron Microscope Based On MEMS

Micro-electro-mechanical system(MEMS)has the advantages of small size,high integration,saving energy,mass production,technologic diversification,high precision,etc.Therefore,it is widely used in many areas such as automobile,aerospace aviation,medical science,communication industry,environmental industry and so on.An integrated test platform worked in TEM has been designed and prepared based on the MEMS.Using this platform,we can in situ observe the high temperature microstructure evolution of micro/nanowires,tapes,fibers and film sample,and simultaneously obtain the mechanical properties.Two kinds of micro-heaters were designed to fit for the Vbeam actuator and the PZT actuator.The platform was fabricated using Silicon-oninsulator(SOI)technique.The top layer has a substrate with thickness of 60 μm.The Pt was selected to be the resistive heating material.There are mainly six photolithographic steps to fabricate the platform.After optimizing the size and structure of the microheater with finite element analysis(FEA),the performance of the heating property of the platform was tested.The results are concluded as following:(1)According to the FEA results,the temperature impact of heating area to other parts of the microheater can be reduced by increasing the numbers,width of heat sink beams and by increasing the gaps between the heat sink beams,simultaneously,the cooling efficiency of the shuttle can also be increased.An inverted-triangle heating area,localized thinning,reducing the heating area size and adjusting the location of heating resistance and temperature sensor resistance contribute to effectively limit the temperature in the heating area,thus reduce the temperature of the rest parts of the microheater.Increasing the thickness of shuttle can reduce the temperature diffusion rate of the heating area.(2)The size of the heating resistance and the temperature sensor resistance can well be controlled with error less than 4%.However,the width of the heat sink beam has an error of 15%,needing to be optimized in size design and process adjustment.(3)The microheater can successfully heat sample up to 600 °C,satisfying the presetting target.Raman Spectroscopy tests and resistance standardization tests can accurately measure the heating temperature of the microheater.(4)The maximum heating speed of the microheater was as high as 426 °C/s under atmospheric condition,and can be stable within 4 second.(5)The microheater has an ability to work continuously for at least 80 hours at 600 °C under vacuum.(6)With this microheater,we are able to finish the tensile test at 600 °C by fitting with the piezoelectric ceramic.